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topic 51925

Inert anode for silver plating

A discussion started in 2009 but continuing through 2019

April 21, 2009

Q. Hi. We've been using silver anode bars in our silver plating. Would it be possible to replace this silver anode bars into inert anodes? We also have existing problem with the increase in the carbonates in our bath. How do we deal with it?

Marylou Bacordio
Process Engineer - Cebu City, Philippines

April 20, 2009

A. Hi, Marylou. It is possible to silver plate with stainless steel anodes, and some shops which primarily do thin silver strikes use stainless anodes. But it is usually less practical than using silver anodes if you do a lot of plating. A 3rd choice would be silver nuggets or "popcorn".


Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha

April 22, 2009

A. Inert anodes causes carbonates to form.

robert probert

Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina

April 23, 2009

A. If your silver bath is sodium based, you can freeze out the carbonates to a degree. It is not a neat or complete process. If you use a potassium based bath, I do not know how you get rid of the carbonates.

James Watts
- Navarre, Florida

Ed. note: see letter 473 for a good discussion of freezing out carbonates.

simultaneous April 26, 2009

A. With potassium cyanide based baths a treatment of calcium nitrate will reduce carbonates to the desired level. I don't have the procedure in front of me, but I have used the process in the past with success. Your silver bath supplier should be able to furnish the treatment procedure for you.

Mark Baker
Fellow Plater - Syracuse, New York, USA

April 26, 2009

A. Stainless steel anodes cause quick rise of carbonates. Don't use them.

To control the carbonates (when silver anodes are used), maintain pH above 12.5 with potassium hydroxide.

Jim, Silver should not be operated with sodium but with potassium cyanide.

sara michaeli
Sara Michaeli sara michaeli signature
chemical process supplier
Tel-Aviv, Israel

simultaneous April 28, 2009

A. I am about to treat our silver plating bath to get rid of potassium carbonate. I am going to use a product called Decarbonator salts SF20522, supplied by Macdermid.
Essentially this is calcium nitrate tetrahydrate.
This will form the insoluble calcium carbonate which settles to the bottom of the tank. The supernatant liquid can be pumped out through a filter.
To remove 10 grams of carbonate, 18 grams of the salts are required. Remember, about 25 g/l of carbonate should be left in the tank to increase conductivity.

Michael Channing
- Southampton, Hampshire, England

April 28, 2009

A. Silver anode itself is a better option which will also reduce cost of production as proprietary silver salt or Silver pot. Cyanide will attract conversion charges as well as conversion loses!

t k mohan
T.K. Mohan
plating process supplier - Mumbai, India

December 16, 2019

Q. What is the best anode for electrodeposition of silver on copper.
We have AgCN KCN and K2CO3 in our bath.
Silver anode is expensive for us.
we are working on electrical elements.

Thank you very much,

mohammad zare
- shiraz, iran

December 2019

A. Hi mohammad. Yes, silver is expensive when you use silver anodes. But it is even more expensive to supply it as a plating salt, and at least four experts have just suggested that you use silver anodes. They don't need to be cast anodes, though; you can use silver "popcorn" in baskets if that's more affordable and available.


pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

May 11, 2020

A. The amount of silver plated on to a workpiece must be replaced, otherwise the plating solution goes out of balance and the silver content is depleted. The cheapest source of silver is silver metal, as silver salts cost about ten times that of their silver content

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

May 11, 2020

A. Hello Mohammad. Ted and Trevor had some great advice, just wanted to mention some advantages of using the "popcorn" type of anodes. Popcorn silver anodes have a greater surface area in bagged anode baskets because of their shape. Secondly , when the cast anodes get thin, in order to maintain your anode surface area you have to either add another full anode next to it or pull it and save it for reclamation. Most silver platers have basket funnels where adding the popcorn material is easier to top off the baskets. Just something to consider.

Mark Baker
Retired - Winston Salem, North Carolina USA

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